We know you are patiently waiting for this feature. This feature is being implemented in stages. Fast tenant switching is currently in testing both internally and with early customers. We expect to release to the public in the Fall. I’ll post an update once it’s rolling out.

Full multi-tenant, multi-user support will be added after fast tenant switching.

Please don't underestimate how many people will be in external teams. With Slack I have 7 different teams I am a member of. I have no problems at all keeping up as the external networks all have badge notifications. This is causing a HUGE adoption problem for the three external projects I'm working on right now where people aren't engaging because they don't get notifications.